DE2851145A1 - PROCESS FOR THE SELECTIVE HYDROGENATION OF GASOLINES CONTAINING AT THE SAME TIME RUBBER-FORMING COMPOUNDS AND UNDESIRABLE SULFUR COMPOUNDS - Google Patents

Description

DR. GERHARD RATZEL

PATENT Attorney File 9400

2851US

November 24, 1978

6800 MANNHEIM 1, Seckenheimer Str.36a, Tel. (0621) 406315

Postal checking account: Frankfurt / M No. 8293-603 Bank: Deutsche Bank Mannheim No. 72/00066 Telegr. Code: Gerpat Telex 463570 Para D

INSTITUT I ¹ RANCAIS DTJ PETROlE

4, avenue de Bois-Preau

92502 RÜEIl-MAEMAISON / France

Process for the selective hydrogenation of gasolines at the same time rubber-forming compounds and undesirable sulfur compounds contain

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The present invention "relates to a process for the selective hydrogenation of a gasoline which contains compounds which form rubber at the same time and undesired sulfur compounds, in particular mercaptans and / or hydrogen sulfide "

It is bekanntj that the methods of pyrolysis or cracking, particularly the cracking with steam supply _s of hydrocarbon feeds such as gasoline and naphtha simultaneously olefins, particularly ethylene, and mineral spirits. It is also known that these gasolines are unstable due to the presence of rubber-forming compounds and that they can be stabilized by hydrogenation in the presence of a catalyst, metallic nickel or metallic palladium or sulphurised cobalt molybdate

In view of the increased cost of crude petroleum and the fractions obtained by direct distillation, the entrepreneurs of pyrolysis factories, especially in the case of cracking with steam j, are forced to use increasingly heavy batches, e.g. gas oils instead of naphtha or the gasoline, the has so far only been used. This leads to an increase in the content of sulfur compounds in the gasolines obtained and, in particular, in the content of mercaptans, the latter being very strong poisons for the hydrogenation catalysts, in particular for metallic catalysts. In addition, the increase in the cracking conditions with steam _p, which is necessary to increase ethylene production, has led to a very considerable recovery of gum-forming compounds such as diolefins _n

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and styrene and indene compounds. These two characteristics make these gasolines difficult to hydrogenate. It should also be noted that for an end use as motor fuels, at least gasoline For the most part, the mercaptans contained therein must be freed, so that there is a negative result in the seal bit test supplies (doctor test).

It is therefore essential that the hydrogenation of the gum-forming Compounds associated with a softening of the gasoline. The methods currently in use generally cooperate Catalysts based on metallic palladium or kickel on supports. In certain cases, catalysts are also used of the Co-Ko, Ui-Mo or M-W type, which are deposited on supports and work in the sulfurized state. These latter Catalysts generally have too little activity to treat pyrolysis gasolines, which are very rich in diolefin, Styrene and indene compounds are. Miekel also has one often too weak activity if the gasoline is rich in gum-forming compounds and mercaptans at the same time. The palladium after all, it has a very good hydrogenating effect, but also has the serious disadvantage of not softening these petrol i.e. the mercaptan content becomes insufficient during the hydrogenation lowered and sometimes even increased, resulting in a gasoline that is unsuitable as a car fuel.

A similar problem is that of pyrolysis or crack gasoline, e.g. from steam cracking, which apart from gum-forming Connections and regardless of presence or absence

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Sound mercaptans containing hydrogen sulfide, for example, 2 ppm or more of _9, for example 5 ppm or more ,, despite the usual Iraktionierungen to which they iferden subjected. Here, too, are the usual catalysts unsatisfactory? With palladium, the total amount of sulfur is not significantly reduced and, moreover, the mercaptan content is usually increased. With nickel, a progressive deactivation of the catalyst compared to the hydrogenation of the rubber-forming compounds is observed.

With the method according to the invention, all these tile parts Fixed. This process consists in the hydrogenation of gasoline with the aid of gaseous hydrogen on two separate catalyst beds. The gasoline and the hydrogen are first passed over a catalyst made of metallic palladium consists of a support, then a catalyst consisting of metallic nickel on a support, namely under the usual reaction conditions for the selective hydrogenation of gasoline, i.e. under such conditions that at least a partial Elimination of mercaptans and / or hydrogen sulfide and also at least a partial hydrogenation of the rubber-forming compounds is guaranteed (which leads to a lowering of the maleic anhydride index MAV) without causing an excessive Hydrogenation of the monoolefins takes place (reduction of the bromine number to less than $ 35, preferably to less than $ 20 of the initial value) .

The usual conditions are well known. They include in particular the following conditions, here only as examples and

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not specified as a limitation are:

- Temperature: 30 to 250 ⁰ C, preferably 50 to 200 ⁰ C;

- Total pressure: 10 to 100 bar, preferably 20 to 50 bar;

- Flow rate or ratio of the volume of the liquid charge (gasoline) to the volume of the catalyst per hour (WH): 0.5 to 10, preferably 2 to 5;

Hydrogen / charge molar ratio (gasoline): 0.1 to 2, preferably 0.5 to 1.5.

It is preferable to work with fixed catalyst beds that can be arranged one behind the other or one above the other in the same reactor or in two or more different reactors.

Understood by the use of metallic palladium or nickel one that initially palladium or nickel is used in a practically reduced state with the exclusion of the same metals, which are completely in the oxide or sulfide state. During the process, the exact condition of the catalyst is little known; for example, there may be limited sulfurization or poor absorption take place of sulfur. Numerous studies have been carried out on this phenomenon, which are not here need to be repeated.

The preferred catalyst carriers are the so-called neutral carriers, i.e. those that have weak or no acidity at all this acidity e.g. through the ammonia absorption test can be determined (Journal of Catalysis, 2.211-222.19 ©)

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The acidity of the carriers used at various stages of the process can be determined by the heat of absorption of ammonia on a carrier at a pressure of 10 "^ mm Hg., The heat of absorption Λ Η is given by the following equation?

heat released (in calories per gram of carrier)

Amount of ammonia absorbed (in millimoles NH, per Grams of carrier)

These two measurements are made by · microgravimetry and by a thermal differential analysis performed at temperature j where the catalyst is to be used.

A carrier can be regarded as practically neutral if Δ H is less than 0.04; it is slightly acidic if Δ Η is between 0.04 and 0.1.

The choice of carrier is not an essential characteristic of the invention. Suitable supports can be refractory oxides or others be refractory compounds of metals of group II, III and IV of the periodic table, e.g. silicates or oxides of these metals; aluminum oxide is preferred, in particular an aluminum oxide with a specific surface area between 30 and 150 m / g, preferably between 50 and 100 m / g.

The methods for preparing catalysts are well known to the person skilled in the art, so that they do not need to be explained in more detail here to need.

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2851H5

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The first catalyst bed preferably occupies 10 to 80% by weight of the total amount of the catalyst, preferably 15 to 40% thereof Lot. The second catalyst bed (or all other subsequent beds) then comprises the remainder.

The first catalyst preferably contains 0.05 to 5% by weight of palladium, preferably 0.1 to 0.5% by weight.

The second catalyst can contain 2 to 50% by weight of nickel, preferably 5 to 20% by weight of nickel.

The pyrolysis gasolines or hydrocarbon fractions in which the invention is particularly applied have a maleic anhydride index (MAV) of more than 10 (mg / g), usually more than 20, and a mercaptan content (calculated as sulfur ) of usually at least 10 ppm _? eg »20 to 250 (they give a positive result in the plombit test or doctor test) and / or a content of dissolved hydrogen sulfide (calculated as sulfur) of at least 2, preferably at least 5 ppm. Such gasolines can contain more than 200 and often more than 500 ppm total sulfur.

They distill, for example, to at least $ 80 between 40 and 220 ^° C. It is nevertheless obvious that lighter and heavier batches can be subjected to the process according to the invention.

Particularly desirable gasolines, which can be produced, for example, by the process according to the invention, have a maleic anhydride index of less than 5 and a mercaptan content of less

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than 10 ppm and give a negative result "in the seal bit test (Doctor test).

Example 1 (comparative experiment)

The "treated batch" comes from steam cracking of gas-oil and has the following properties:

Characteristics method Results Volume mass, at 15 ° C NP T 60-101 0.859 Distillation ASTM ° C NP M 07-002 Starting point
_50/0
End point 55
111
180 Total sulfur (ppm) NP M 07-014 1500 H ₂ S - sulfur (ppm) <2 Mercaptan sulfur (ppm) NP M 07-031 70 Corrosion Eupferplatte NP M 07-015 1b Seal bit test (doctor test) NP M 07-005 positive Bromine number (g Br / 100 g) NP M 07-017 52 Maleic anhydride index
(MAY) mg maleic anhydride / g UOP 326-58 97 Induction period (mn) of 20 ppm
Antioxidant (N N'-di-sec.-butyl-
p-phenylenediamine) NP M 07-012 20th Octane number "Research" (0.05 wt .- /
Lead tetraethyl) NP M 07-026 98

This gasoline is allowed to mix with hydrogen through a

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/! Z

Flow reactor which is filled exclusively with a catalyst which consists of 0.3 wt .- $ palladium, which is deposited in the usual way, starting from palladium nitrate, on an aluminum oxide support with 70 m / g specific surface area. The acidity of the alumina in the above ammonia absorption test is UE = 0.03. "Before use, the catalyst is calcined for two hours at 45O ⁰ C and then reduced for two hours at 100 ⁰ G with hydrogen.

The reaction conditions are as follows:

- Flow rate (Vol / Vol / h): ... 2

- mean temperature ( ⁰ C): .. ". <> 130

- Total pressure (bar): 40

- H ₂ / batch (mole): "0.5

The product obtained after 100 hours of operation has the following essential properties:

- Bromine number (g / 100g): 40

- MAV (mg / g): 2

- Induction period (mn) with 20 ppm antioxidant: 540

- Mercaptan sulfur (ppm): 100

- total sulfur (ppm): 1500

- Copper plate corrosion: 1b

- Seal bit test: positive

- Research Octane Number: 98

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Firmly ₉ that one can hydrogenate the gummiMldenden compounds practically Toll Employed with this catalyst to set (MAV = 2) that, however, no reduction in the mercaptan content is carried out (Rather, "is observed an increase of this content), the gasoline obtained can not be used as a car fuel _e

The test is continued for a thousand hours and practically the same characteristics of the hydrogenated product are obtained within the accuracy of the analyzes _{or the like}

Example 2 (comparison test)

Hydrogenating the same fuel as in Example 1 in a reactor, which is filled exclusively with a catalyst _o of 10 wt - is $ nickel, which is deposited in the usual way, starting from Mckelnitrat, on an identical support as in Example 1 , and is then calcined for two hours at 500 ⁰ C and then reduced fifteen hours with hydrogen at 40O ⁰ C.

The reaction conditions used are the same as in Example 1.

The product obtained after a hundred hours of operation has the following essential properties:

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If

- Bromine number (g / 100 g): ............ 43

- MAV (mg / g): .... " 10

- Induction period (mn) with 20 ppm antioxidant: 480

- Mercaptan sulfur (ppm): ...................... 6

- Total sulfur (ppm):, ......., .. »... 1500

- Corrosion of copper plate: ................ <,., ..... 1a

- Seal bit test: "......... *. negative

- Octane number "! Research": 98

It is found that the hydrogenation of the gum-forming compounds is considerably less than in example 1 j it is actually insufficient, since in general the τοη according to this Process type Workers required MAV value less than Must be 5

In contrast, it is observed that the product softened compared to the batch and corresponds well to the required specification for fuels.

The test continues for a thousand hours; the MAV of the hydrogenated Product is 15 after this time here a certain deactivation of the catalyst is found.

Example 3 (according to the invention)

The same gasoline as in Example 1 is treated in the presence of hydrogen in a reactor with two catalytic beds

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contains. The first comprises a third of the total volume and consists from the reduced palladium catalyst according to Example 1, the second comprises two thirds of the total volume and "consists of the reduced nickel catalyst according to Example 2.

The reaction conditions are the same as in Examples 1 and 2. ■

The results are given in Table I.

Example 4 (comparative experiment)

Example 3 is repeated and the Kickel catalyst is first placed in the reactor (1/3 of the total volume) and then the palladium catalyst (2/3 of the total volume), the catalysts and the reaction conditions remain the same. The results are given in Table I.

Example 5 (according to the invention)

Example 3 is repeated with modification of the proportions of the catalysts: 15% by volume of palladium catalyst and then 85% by volume nickel catalyst. The other conditions remain unchanged. The results are given in Table I.

Example 6 (according to the invention)

Example 3 is repeated with modification of the proportions

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Niss of the catalysts: 50 vol .- $ palladium catalyst and then 50 volume $ Mckel catalyst. The other conditions stay unchanged. The results are given in Table I.

TABLE I.

Results after 100 hours of operation?

Examples:

Bromine number (g / 100 g) 42 41 45 41 MAV (mg / g) 3.5 2.5 4.8 2.7 Induction period (mn)
with 20 ppm antioxidant 500 540 480 530 Mercaptan sulfur (ppm) 7th 20th 4th 9 Total sulfur (ppm) 1490 1500 1490 1500 Corrosion copper plate 1 a 1 a 1 a 1 a Seal bit test negative positive negative negative Octane number "Research" 98 98 98 98

It is found that only the products of Examples 3, 5 and 6 at the same time meet the requirements for MAV, mercaptan-sulfur and plombit test.

The experiment according to Example 3 is continued for a thousand hours and the product still meets the requirements: MAV = 4.5, seal bit test = negative, mercaptan-sulfur = 8 ppm.

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Examples? up to 10

These examples relate to the Pail of a gas which is relatively poor in mercaptans but contains dissolved Scliwefelwasserstoff _s. This gasoline comes from the cracking of naphtha with steam.

Composition of the batch §

Volume mass at 15 ° 0 .ρα _Ο <, _β ·. _ο .. <> · β. _βΛβ ... 0.830 Distillation ASTM ( ⁰ C) ..., ... <, .. · .... 55-199 Total sulfur (ppm) o _O ... · .. · ...... .. <><.. 310 mercaptan sulfur (ppm) """."", - _β " _ββ .-. »Ο». «.«. 8 dissolved HpS sulfur (ppm)? ·. _ββ οοό * <><><> «10

IYLnLV ^ mg / gj οοββ «ββ» βοοοβοο OO ocroooeooBeeo.o ^ O

Bromine number (g / 1 OO g) oooeooooesceoeoooooooo »38 seal bit is _β . _βοο · _β ... · ... ο «.. · .. _β0 ο ... positive

The reaction conditions are as follows;

T = 10O ⁰ Cj total pressure = 30 bar? Flow rate 2 vol / vol / h; _{H 2} / gasoline molar ratio _{= 0 s} 5.

The catalysts are the following?

example

7 (comparative experiment) ... catalyst according to example 1

8 (comparative experiment) ... catalyst according to example 2

9 (according to the invention) 25 vol .- # palladium catalyst according to Bet

game 1, then 75 vol .-% nickel catalyst according to example 2 909823/0659

10 (comparative test) ... 75% by volume, - $ Hiekel catalyst according to

Example Z ₉ then 25 vol .- $ palladium catalyst according to Example 1

The tests are the same as described above. The results are given in Table II.

after TABLE II MAV after 1000 hours DT 50 hours 1.5 DT R-SH MAV example + R-SH 5 + 18th 2.5 7th 18th 3.5 - ^ 5 15th 8th - £ 5 3.5 ^ 5 4.5 9 5 - ^ 5 12th 10 5

DT = seal bit test (result: + or -)
R-SH * content of mercaptan schvrefel (ppm) MAT (mg / g)

Only the catalysts of Examples 8 to 10 deliver after 50 hours of operation acceptable results, but a strong deactivation of the catalysts of the examples is then observed 8 and 10. Only the catalyst according to Example 9 is stable with regard to the softening and the hydrogenation at the same time.

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Claims (1)

145 Claims Λ / - Process for the selective hydrogenation of a gasoline which simultaneously contains (a) monoolefins ,, (b) rubber-forming compounds and (c) at least 10 ppm mercaptans and / or gives a positive result in the plombit test, this gasoline being with Mixed hydrogen ₉ passes through a metallic hydrogenation catalyst in contact,
characterized ₉ that this passage _g initially carried out at a temperature of 30 to 25O ⁰ C, over a catalyst of metallic palladium on a Sräger and then over a catalyst ,, the metallic Iiekel on a FRÄGER ^ contains so that the gum-forming compounds is eliminated and the mercaptans removed or the plosabit = ü! est becomes negative ^ without excessive hydrogenation of the monoolefins taking place " 2ο procedure according to claim 1 "
characterized by _s
that one works at a temperature of 50 to 200 ⁰ G ", 3ο method according to claim 1 or 2 ₉
characterized by ^ that the gas to be treated is a maleic anhydride index of greater than 10 mg / g and a Mereaptan-Sehalt (calculated as sulfur) of at least 10 ppm has _ö so that a positive result of the normalized Ploiabit °! Eests is obtained " 10 9 823/06 ORfGlMAL INSPECTED 4. The method according to claims 1 and Z ₉
characterized, that the gasoline to be treated has a maleic anhydride index of more than 10 mg / g and a content of dissolved hydrogen sulfide (calculated as sulfur) of at least 2 ppm. 5. The method according to claims 1 Ms 4 _P
characterized by _P that the catalysts are arranged in a fixed bed. 6. Process according to claims 1 to 5 _p
characterized, that an aluminum oxide is used as a catalyst support ₉ which has a specific surface area of 30 "to 150 m / g and an acidity of less than O ₉ 4 (measured as Δ Η in the ammonia absorption test» 7. The method according to claims 1 "to S ₉
characterized ₉ that the PalladiUE catalyst and the ETielcel X catalyst occupy 10 to 80fo and 90 to 20 $ of the total volume of the catalyst, respectively. 8. The method according to claims 1 to 7 _S.
characterized, that the palladium catalyst and the nickel catalyst 15 to 40 $ and 85 to 60 $ of the total volume of the catalyst, respectively take in. 909823/0659 = 3- 2851U5 9 »process according to claims 1" to _S 8 characterized in that the first catalyst _s O ₅ 05 wt .- ^ Ms 5 palladium and the second catalyst 2 Ms 50 percent by _e -? £ contains nickel. 10. The method according to claims 3 or 4 _S, characterized ₉ that the reaction conditions are chosen so that a gasoline with a maleic anhydride index of less than 5 mg / g and a mercaptan content (calculated as sulfur) of less than 10 ppm receives, whereby this gasoline gives a negative result in the normalized seal bit test. 909823/06